Percussion tool



J. H. ANDERSON PERCUSSION TOOL Feb. 5, 1952 Filed June 17, 1948 2SHEETS-SHEET `J. H. ANDERSON PERCUSSION TOOL Feb. 5, 1952 Filed June 17,1.948

2 SHEETS-SHEET 2 r @n T w NA L vn ma. m a a HIS ATTORNEY.

Patented Feb. 5, 17952 UNITED sTATEs PATENT oFFicE I v 2,582.1,246 1 lPERCUSSION TOOL James Ht Anderson,Y Easton, Pa.,a'ssig11or toIngersoll-Rand Company, New York, N...Y., a

corporation ofNewJei'seyy i i Appucatitn'Jun-e rz, 194s, serial No.tasti .13 claims. (c1.121.....5.)k

This invention relates topercussion'tools, and i more particularly .to auid .actuated rock drill and means for feeding the 'working implement ofa rock drill into its work.

Heretofore such means were generally of either the type. incorporatinga. chuck geared directly to a driving means', or the .familiar riebarratchetarrangement. Both of these types have v recognizeddisadvantages.

,In the first. casea. motor of greater horsepower .-than.. is normallyneededy for rotating vthe working implementwas required in order torprevent the working implement from sticking or binding in thel hole,andthereforaat best, it was an inefficient. and bulky arrangement.. Inthesecond case,..because of the. structural weakening eifectofay largecentral bore or hole in the, piston [for the ,rifle bar, the piston. is,fior the same output, of greater 4size. and Weight than a solid pistonor apiston with a relatively small waterholetherethrough. In thepresent' invention the previously mentioned and other disadvantages areeliminated:

by feeding theworking implement of a rock drill through a novel feedscrew-feed nut arrangementin which the-nutl isv geared' toY the chuck.Inr this arrangement the feed nutA and screw are rotated in the samerdirectionjat highspeeds but with` a low speed' differential. Thus ahigh gear ratio may be obtained which. permits the 'use'of a relatively'high speed-low horsepowerdriving motor for the. feed nut and screw. A`further increase in the gear ratio betweenk thev driving motor andthefeeding.' means is obtained by rotating the feed nutthrough a. doubleplanetary gear system, driven directly by the motor, and by rotating.the feed' screw. through a second double planetary gear system. Thesecond gear system is, in this.instancapowered'by the .driven l member.of a. coupling in which. relative yrotation or slippage occurs between..the. driving and the drivenA members..l such as aA fluid or magneticcoupling, for the. purpose ofpermitting dual con trol of the reverse.feedingl ofthe tool vor working implement. "I'hat is, by providing abrake means at thel end' of the shell; fthe fefe'dscrewcan 15e-heldagainst rotation,v duef Yto slippage', inthe coupling.

thereby reversing. the 'relative 'speedjrelaton'b tween the feed nutand'screw which reverses the motion lof' they working implement; and asecond controll may', be provided at ther` tool that will changetherelative speeds of the gears injthe planetary'systems and thereby'increasel the speed of rotation of 'the' feed nut and halt the'rotation1 off the1 feed screw tcly reverse` the retelling ofthe workingimplement'.V

In addition to the above arrangement, means are provided in cooperation.with the feedr nut which" utilizesl the riovve'i.-rnormally-'dissipatedin theA vibration-of' the. tool to" supplement the.power of theV driving-rn'otor.V Hence a smaller 'motor may' be used toVrotate the Workingiimplementin that the vibration'. 'of the toolwillaid'the motor in preventing sticking'orbinding ofthelworking implement.Moreover'this means' hasvthe'added advantage of' 4vreducing. or'dampening thel vibrations of thedrill. Y l

It is, therefore, 'one object of myinvention to reduce'the vibration: ofa rock'. drill?.

A :second object Yof my 'invention' to utilize thev recoilof apercussion tool to intermittently rotatetheworking. implement.

Another object is to reduce' theA directfdmpact onthe feed'snuti andthefeed screw by the drill,

dueto the-reactionI impact thereof.

Another object is to provide a mechanism .@ther* objects Awill'.A be infpartobviousv` and part pointedy out hereinafter.

InV the drawings Aaccompanying this. specificata ticnandl imwhichr'similar' referencey numerals refer'"tcr'sirriilarpartei` f- Figurer-1iis-v 'a'f side'y Iiew;v partly in. section, fora rock drill'` mountedafwerking position,I

Figure. 2 is'v a'- longitudinal. elevation;in".Y section'. of a rockdrill embodying the presentinventio'rn vnvFigurel I3 is a: sectionalview' of af- `fluid; coupling, 1 Figure 4i is: ai" transverse view'taken' through' Figure'2alo1fig':theliruelnal,L

.FigureI 5? isA a: 1transversefvievr' takenfthrogh Figure: 2alongthel'ine'S-s and shows' .a planeV tarygavtmm f Figuren? is.- a-transversevew takenthrougn Figure zfaiongfthe iinel t-t andt shows"A atrain similar tc-thatinrigure. f Figure .'isi transverse. view rakenlthrough Figure? 2 along the line 'IL-T, and

Figure 8 is a transverse view taken/'through with the feed screw I8.

Mounted on the rear end? of :the shell. Il is 1a brake 20 which providesamanual control over the rotation of the feed screw I8. The brake showncomprises a split ring 2 I whichr encircles a smooth portion on the feedscrew I8 and has radially extended end portions 22 arranged inparallelism and extending into a recess 23 in the shell I I. A bolt 24passes through said end portions22 andone end is threaded in the shellso that rotation of the bolt 24, by means of the handle 25 on the otherend of the bolt 24, in one direction brings a shoulder 26, on the bolt,to bear on one of the end portions 22 and forces it toward the otherportion 22, held from movement by the material which forms the-side ofthe recess 23, land thereby effectively clamps 4the feed screw I8against rotation. Rotation of the bolt 24 in the opposite directionreleases therbrake 28 so that the-feed screw I8 is free to rotate.

Rotary motion is imparted to the feed screw I8 by means ofV a geartrain. comprising an epicyclic train 2l and a gear 28 which looselyencircles the feed screw I8 and carries a key 29 whichslides in aIkeyway 30 that extends along substantially theentire length of the feedscrew I8 in order to permit endwise motion of the feed screw. --Rotarymotionv is imparted to thefeed nut I9 throughV a Vsecond -gear traincomprising an epicyclic train 3| and a gear32formed on the end-of anextension33, on the feed nut I 9,which encircles the feed screw I8 andis in spaced relation therewith. Y. The epicyclic train,designated ingeneral by 3 I, that rotates the feed nut I9 is, in this instance, ofthe dual planetary type and is driven directly by agmotor'34 positionedrearwardly of the back head I6. The motor '34 bears against an end plate9 which forms a closure forthe chamber I'I-and has a Ycentralperforation for the motor shaft 35 which extends, succeedingly, throughthe train 21, a iiuid coupling 36 and the train 3I, in the chamber I'I,and issupported by a bearing 31 at the opposite or forwardly end of thechamber II. v

y The coupling 36 is of the usual fan construction and has a drivingmember or fan 38 keyed to the shaft 35 and a ldriven member or fan139,which are hydraulically associated-that is, torque is transmitted fromthe driving member to the driven member through a luidmedium in thecoupling." In` this instance, the housing 48, ofnthefcoupling 36,.formsa part ofthe driven member and is provided Vwith a-rearward extension4I"to,which is-adapted adriving or central gear 42 of the train 2'Iwhich rotates the feed screwIB. .I qu' 'n y y I' -1 .'The central ordrivingV gear 42, forthe train 3 I, is formed on the shaft 35, forwardlyof the coupling `36; and is adapted to vrotate a planetary gear-43 whichin turnfdrivesran orbital gear 44 having external teeth. 45 --that areinterlocked with @weer frrrotetina.the-feednut The 4 external teeth 45are of somewhat greater width than the teeth on the gear 32 in order topermit endwise motion of the orbital gear 44 resulting from thevibration of ithe drill.

In the present form of the invention there are three such planetarygears 43 held in a spaced 4.relation around the shaft 35 by means of astabilizing member 4,6. The'member 46 encircles the shaft 35 and isadapted 'on-` receive pins 4'I which serve as axles for the planetarygears 43 and for areduced portion or extension on the planetary gear 43whichforms a smaller planetary gear 48 that is interlocked with anorbital gear 49 of somewhat lessdiameter than the orbital gear 44. vThesmaller orbital gear 49 is prevented lfrom Y rotating byafbrakemeans 58,described in detail hereinafter, thereby causing the gear 48 and thelarger planetary gear 43 to travel around the brake means designated 'ingeneral by 50.

shaft 35 in a direction opposite to the rotation of the orbital gear44.; This means, of course, that the speed of rota-tion of the orbitalgear 44 is slower than when the smaller orbital gear 49 is released, bythe brake means, to rotate freely and the axis of the planetary gear 43is held stationary by said brake means. .l

In order to obtain this speed controlof the orbital gear 44 oreffectively of the yfeedfnut gear 32 it drives, rotary motion of themember 46,

imparted thereto by the 'action of the small planetary gears 48traveling within the smaller orbital gear 49, is controlled by the airoperated The brake means 50, in one control position, prevents therotary motion of Ithe orbital gear 49, which requires, of course, thatthe member 46 rotate whenever the planetary gear 43 is rotated; and inthe other .control position permits the orbital gear 49 to rotate freelyand'at lthe same time holds the stabilizing member 46 'against rotation.

The brake means hereinl shown consists of a brake member 5I whichencir'cles the iluid coupling 36 and rests on an annular support member52 interposed therebetween. A rim 8 on the Y support member 52 limits'the rearward movement of the brake V`5 I, and the support member 52, inturn, is held against such movement by a ring 5,3 that extends into thechamber I'I from a groove in the inner surface ofthe back head I6. Thematerial bounding a groove 54 Iin the outer periphery of 'themember5|cooperates with the inner surface of the back head I6 to define apressure chamberY which is divided into compart-V ments 55 ,bylanannular ring 56 secured to the back head by means of :bolts 5l. In orderto prevent leakage ofpressure fluid from the compartments, the ends ofthe material which forms the sides of the rgroove 54 are'recessed toreceive a sealing material 58 which seats against the inner surface ofthe back head I 6. The forward end of the brake 5I bears against a. rim59 on the smaller orbital gear 49 yand has an'inwardly extended flange60 which overlies an .outwardly extended flange 6I on the stabilizingmember 46. I

With this arrangement, by.A valving air, into the forwardfcompartment'55and exhausting it from the rearward compartment 55by means of aj two-waycontrol valve 62 in the back head I6, the' -pressure fluid "acting, onthe material forming one' side ofthe groove 54, forces the brake member5I forwardly against the smaller orbital gear 49 and moves it intofrictional engagement with@ ring'u53, similar to theraforenlentionedring 7.53, thereby effectively holding the orbital gear 49 fromrotating. this brake feed nut I9, is rotated at its'lower'speed.

In the other position of :the'valve 62,:pressure fluid is conductedtothe rearward compartment 55 andfexhausted from the forward compartment55 thereby forcing lthe brake'memberil' in a rearwardly direction whichreleases the orbital geart9 and brings the flanges 60 andjBI intofrictional engagement and clamps .the stabilizing member I6 against thehousing lil ofthe fluid coupling 36 thereby effectively halting rotationof the member liand'the driven member 39 of the coupling 36. In .thisbrake position the feed nut I9 rotates at its higher speed and also,'1itis to be noted, the train 21 or effectively the. rotation of the feedscrew I8, is halted.

The `train 27 is similar inconstruction to the train 3| and it is .alsosimilar Vin operation to that of the train3| when the brake member 5| isin its forwardly control position. Accordingly,

' the discussion of the construction and operation of the train 27 kwillbe minimized and the .designation of the similar. parts of the two.trains will be identical with the exception that the numerals referringto the members comprising the trainZ'I will be primed. The material.difference between the two trains 2'I-.and 3| is that the smallerorbital gear .49- is secured to. the back head I6 and is atall timesprevented from roe tary movement land the relative sizes of the gears inthe train 2Idiffer somewhat from those in the train 3| so that thelarger orbital gear 44' which is engaged with the .gear 28, that rotatesthe feed screw, turns at a higher speed than does the orbital gear Mthat isengaged with the gear.32, that rotates the feed nut. .Because ofthis relative difference in speeds of the feed nut and the feed screw,the feed nut will have a tendency to advance.V along the feed screw.

In order to utilize this advancing and rotary motionof the feed nut,the. outer surface of the feed nut I9 is provided with splines v63 whichare adapted. to engage a means whereby such moe tion may be utilized tofeed the rock drill into its work. This means Valso utilizesthevibratory motion .of the rocky drill,:due to. the. reversals .of thepiston I3, to intermittently rotate a work: ing implement 54. Suchmeans. comprises a cylindrical member 65 having fiutes. 66 inythe innersurfacevthereof tocooperate loosely vwith the splines 63, and gearteeth. 6,1 formed on the outer surface to engage with a gear. formed ona chuckV 69 in theA fronthead 'l0 ofthe drill Ii). A radial arml 'II on.the drill IIIpartially en.-4 closes the cylindrical member 65 andmaintains a sliding engagement with'the opposite end surfaces thereof,thereby preventing endwise motion and permitting rotary motion of the.memer ber iwith respect to the drill.

In operation, assuming that air has been valved into .the forwardcompartment-5j5., :the brake v5I] will preventrotation of. the smallerorbital gear 49 and permit rotation of the-sta.- bilizing member 46 andthefluid couplingl. The feed screw |8.wi1l, then, rotate at `-a...rela.tively higher speed than the feed nut. 9 thereby advancing the feed nutI9 along the feed screw IB to move the working'implement'll into itswork. Atthe same time, the rotationv of the feed nut I9 will rotate thecylindrical member 65 which, in turn, rotates the chuck 69 orVeffectively, the working implement.v Howeverfthe rotation of the chuck|39,` due to the rotation of the feed nut. I9, is. intermittentlyaccelerated and halted by ythe actionof.. thev cylindrical meme ber 65in response to the vibration of the drill I9. That is, assuming that thepiston starts on its" forwardstroke, the reaction of the, drill lII) isin the opposite direction. which drives the cylindrical member 65rearwardly against the splines 63 thereby increasing the rotary speed ofthe Acylindrical member 65. The rotary speed of the cylindrical member65 relative to the. chuck 69 is, during its backward motion, the sum ofthe speeds imparted thereto by the rotation ofthe feed nut I9 and therotation imparted tothe member 65 as it is driven along the splines.

When the hammer piston I3 strikes its blow and starts on its rearwardstroke the reaction f movement of the drill I0 and the member 65 isforwardly and thus the flutes |56 move away from the splines 63 on thefeed nut I9 thereby momentarily halting the rotation of the chuck6`9'until the rotation of the feed nut I9 moves the splines 63 onceagain into engagement with the surfaces which form the sides of theflutes 66. The time interval during which rotation of the chuck isinterrupted is, of course, dependent on the' fit which exists betweenthe splines 63 and the flutes 65.

In the event it is desirable to retract the working implement from itswork, it is merely necessary to change the setting of the valve 62thereby communicating pressure fluid with the rearward compartment whichmoves the brake member 5t rearwardly to halt the rotation of thestabilizing member 46 and the driven member 39 of the fluid coupling 36and also to free the smaller orbital gear 49 to permit rotation. Thisaction increases the speed of the larger orbital gear 44, in that theplanetary gears 43 are now held from rotation around the shaft 35, andat the same time halts .the rotation of the gear train 21 that drivesthe feed screw I8. Under these conditions, the relative rotation betweenthe feed nut I9, and the feed screw I8 is reversed and greatly increasedthereby reversing the direction of movement of the feed nut I9 along thefeed screw I8 and at the same time greatly increasing the speed of thislongitudinal motion of the feed nut I9 in comparison to the normalforward speed thereof. l

It is to be noted in this connection, that the reversal of and increasedspeed of the longitudinal movement of the feed nut, and hence the drill,along the feed screw occurs without change in the speed of the motor.For example, assume that boththe feed nut and feed Screw are driven inthe counterclockwise direction (as viewed looking forward along thedrill from the backhead), the nut being driven at 230 revolutions perminute (R. P. M.) and the screw at 250 R. P. M. VThe relative speed ofthe screw to the nut is 2O R. P. M. and the nut will move slowly forward(at about 20 inches per minute) `along the feed screw.

When,` however, the brake 5I) is positioned to halt the rotation of thefeed screw, the Yrelative speedbetween the screw and nut is reversed-i.e., the nut is now moving 230 R. P. M. faster than the screw.Accordingly the direction of longitudinal movement of the nut relativeto the screw is reversed so that the nut now moves in the rearwardlydirection along the screw at a speed some 10 times as fast as itsforward direction. However, due to the shifting of the brake 59, theplanetary gears 43 areprevented from lmoving in a circular path aboutthe shaft 35 and accordingly the speed of the orbital gear,` 44 isyincreased so that the feed nut is new driven 7 at a higher speed, say1800 R. P. M., thereby increasing the reverse longitudinal movement ofthe drill, relative to the screw, over that attained by merely haltingthe rotating of the feed screw. The change in relative speedbetween thefeed nut and the feed screw due to the halting ofthe rotation of thefeed screw is, of course, in no Way dependent on the speed of the motor,and the increased rotational speed of the feed nut is due entirely tothe change in gear ratio in the gear train 3l in the manner previouslydescribed.

Such reversing motion may also be accomplished through the brake meansprovided on the back of the shell il, by merely applying the brake 20which will halt the motion of the feed screw IB and thereby reverse therelative rotation between the feed screw i3 and the feed nut i9 which,of course, reverses the direction of longitudinal motion of the feed nuti9. The speed of reverse movement attainable in the latter method ofreversing the direction of moe tion of the rock drill is not as fast asthat obtained by the rst method, however it can be accomplished when thesetting of the valve 62 is such that the forward compartment 55 isexposed to fluid pressure.

To be noted here, also, is that the heavy spring or other buffernormally found on the back end of the shell to halt the reverse motionof the rock drill has been eliminated by virtue of the iiuid couplingarrangement. That is, due to the hydraulic association between thedriving and driven members 38 and 39 of the coupling 35, slippage willoccur therebetween when the rock drill reaches the end of its travel onthe shell l l. Such slippage prevents excessive strain on the variousmembers of the drill that cooperate to impart reverse motion to thedrill.

Itis now obvious that the present invention presents several distinctadvantages over other rock drills and it is a distinct contribution tothe eld to which it appertains.

While I have 'shown and described one form of my invention it is to beunderstood that various changes and modifications may be made thereinwithout departing from the spirit of the invention as set forth in theappended claims.

I claim:

l. A fluid actuated tool comprising a casing having a bore, a front headthereon, a reciprocative piston in the bore, a working implement in thefront head to receive blows from said piston, a spirally splined membermounted independently of the casing, a uted member engaged to thesplined member and engaged against longitudinal movement with respect tosaid casing, and a gear on the last said member engaged to rotate saidimplement, the fluted member being actuated by the vibration f the toolresulting from reversals of the piston for imparting intermittent rotarymovement to the working implement.

2. Means for rotating the working implement of a percussion tool,comprising a splined member, a uted member interlockingly engaged withthe splined member and engaged to said tool against longitudinalmovement between the tool and the splined member, gear teeth on saidluted member, and a chuck for the working implement having gear teethengaged with the first said teeth.

3. A rock drill comprising a casing having a bore, a front and back headon the casing, a reciprocatory piston in the bore, a working implementto receive blows from the piston, a chuck in the front head for holdingsaid implement, a

motor in the back head, a fluid coupling driven by the motor, a feed nutengaged to said casing to impart longitudinal movement thereto, a geartrain driven by the motor and engaged to the feed nut for rotating thefeed nut, a feed screw mounted `independently of the casing and threadedin the feed nut, a gear trainvdriven by the coupling for rotating thefeed screw at a faster rate than the feed nut, and a gear engaged tosaid chuck and in threaded engagement with said feed nut and rotatedthereby for rotating said chuck, said gear acting responsively to thevibrations of the rock, drill .for accelerating and interrupting saidrotation of the chuck.

4. A rock drill comprising a casing having a bore, a front andback headon the casing, a. reciprocatory piston in the bore, a working implementto receive blows from the piston, a chuck in the front head for holdingsaid implement and having a gear thereon, a motor in the back head, afluid coupling driven by the motor, a feed nut having splines on theouter periphery thereof, a gear train driven bythe motor and engagingsaid nut for` rotation thereof, a feed screw mounted independently ofthe casing and threaded in the feed nut, a gear train driven by thecoupling and `engaged to the feed screw for rotating the feed screw at afaster rate than the feed nut, anda member having flutes slidablyinterlocked with the splines on said feed nut and having a gearinterlocked with the gear on said chuck.

5. A fluid actuated tool comprising a casing having a bore, a front andback head thereon, a reciprocatory piston in the bore, a workingirnplement in the front head to receive blows from the piston, avlongitudinally disposed feed screw mounted independently of the casing,a feed nut on the screw and engaged to said implement and engaged to thecasing against longitudinal movement between the casing and the feednut, a motor in the back head, a coupling driven by the motor, a geartrain driven by the coupling and engaged to the screw for rotationthereof, a gear train driven by the motor for rotating the feed nut. anda brake arranged to engage a gear in the second said train for varyingthe relative rotational speed of some of the gears in the second saidtrain for retracting the working element from a work piece at a ratewhich exceeds the advancing speed of said implement at the same motorspeed.

6. In a percussion tool, a casing having a bore, a front head, a pistonin the bore, a working implemcnt in the front head to receive blows fromthe piston. a feed screw mounted independently of the casing, a feed nutthreaded on the feed screw and engaged to said casing for impartinglongitudinal movement to said casing, a motor geared to said nut andscrew for imparting rotary movement thereto, and a member engaged to thecasing against longitudinal movement relative thereto and threaded onsaid nut and engaged to saidV working implement to transmit the rotarymovement of the screw to the working implement and actuated by thevibration of the tool for rotating said implement.

7. A fluid actuated drill comprising a shell, a casing slidable on theshell andphaving a bore for a reciprocatory piston, a working implementat one end of the casing, a chuck for rotating said implement, a motorat the other end of said casing. a longitudinally disposed feed screwmounted on the shell, a fluid coupling driven by the motor, a gear traindriven by the coupling and engaging said screw `for rotation thereof, afeed nut on the screw, a gear train driven by the motor and engaged tosaid nut, a member in slidable interlocking engagement with said nut andthe chuck and engaged against longitudinal movement with respect to saidcasing for rotating the chuck, and a brake on an end of the screw forpreventing rotation thereof to reverse the longitudinal movement of thecasing.

8. In a fluid actuated tool, a casing having a bore, a front head on thecasing, a reciprocating piston in the bore, a working implement in thefront head to receive blows from the piston, a longitudinally disposedfeed screw mounted independently of the casing and against longitudinalmovement, a feed nut threaded on the feed screw, a motor engaged to saidscrew and nut for imparting rotary movement to the nut and the screw formoving the nut longitudinally relative to the screw, a member slidablyengaged to and rotatable with said nut and locked against longitudinalmovement with respect to said cas ing for imparting longitudinalmovement to the casing relative to the screw, said member being rotatedrelative to said nut in response to vibrations of the casing due toreversals of the piston, and a gear on said member engaged to rotate theworking implement.

9. A percussion tool comprising a casing hav ing a bore, a front head onthe casing, a piston in the bore, a working implement in the front headto receive blows from the piston, a motor mounted on the casing, a fluidcoupling driven by the motor and having a driven member, a feed nutengaged to said casing and said motor, a feed screw mountedindependently on the casing against longitudinal movement relativethereto and threaded in said nut and engaged to said driven member, abrake on the casing adapted to engage said driven member to preventmovement thereof, and a brake on the feed screw to halt the rotationthereof.

10. A fluid actuated tool comprising a casing having a bore, a front andback head thereon, a

reciprocating piston in the bore, a working implement to receive blowsfrom the piston, a chuck in the front head for holding said implement, amotor in the back head, a hydraulic coupling driven by the motor andhaving a driven member, a longitudinally disposed feed screw mountedindependently of the casing, and against longitudinal movement relativeto the casing, a feed nut threaded on the feed screw, a member threadedon said nut and engaged to said casing against longitudinal movementtherebetween and engaged tc said chuck to impart rotary movementthereto, a gear train driven by the motor and engaged to the feed nutfor rotating said nut, a gear train driven by the driven member andengaged to the feed screw to impart rotary movement thereto foradvancing the Working element into a work piece.

11. A fluid actuated percussion drill compris- Cfu eti)

10 ing a shell,v a casing slidable on the shell, a longitudinallydisposed feed screw mounted on the shell, a feed nut threaded on thescrew and engaged to said casing to prevent longitudinal movementbetween the nut and the casing, a gear train engaged to said nut forrotation thereof, a motor mounted on the casing and engaged to drivesaid train, a gear train engaged to said screw for rotation thereof, aduid coupling driven by said motor and engaged to drive the last saidtrain, a brake arranged to engage the coupling and a gear in the firstsaid train to halt the rotation of the feed screw and increase therotational speed of the feed nut for reversing the longitudinal movementof the feed nut on the feed screw, 'and a brake on the feed screw tchalt the rotation thereof.

12. A fluid actuated drill comprising a shell, a casing slidable on theshell and having a bore with a reciprocating piston therein, a workingimplement at one end of the casing, a chuck for rotating said implement,a motor` at the other end of said casing, a longitudinally disposed feedscrew mounted on the shell, a :duid coupling driven by the motor, a geartrain driven by the coupling and engaging said screw for rotationthereof, a feed nut on the screw, a gear train driven by the motor andengaged to said nut, and a member in slidable interlocking engage mentwith said nut and the chuck and engaged against longitudinal movementwith respect tov said casing for imparting rotational movement to thechuck in response to vibrations of the casing.

13. A fluid actuated tool comprising, a shell, a casing slidable on theshell and having a bore with a reciprcc'atingpiston therein, a workingimplement at one end of said casing, a longitudinally'disposed feedscrew mounted on the shell, a motor engaged to said screw for rotationthereof, a feed nut threaded on said screw, a coupling driven by themotor and engaged to said nut for rotation thereof, and a memberthreaded on said nut and engaged to said working implement for rotationthereof and engaged to said casing to prevent longitudinal movementbetween the casing and said member.

JAMES H. ANDERSON,

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 308,524 Sergeant Nov. 25, 1884:815,299 Leyner Mar. 13, 1906 1,832,471 Nell Nov. 17, 1931 2,124,627Morrison July 26, 1938 2,236,700 Slater Apr. 1, 1941 2249,639 SheetsJuly 15, 1941

